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Genera in the tribe Pyroleae (subfamily Monotropoideae, family Ericaceae) occur as understory plants in northern temperate zones where some form major components of ecosystems. Most have been poorly studied in terms of their association with symbiotic fungi. In this study, colonization patterns of mycorrhizal roots of five members of the Pyroleae (Pyrola asarifolia Michx., Pyrola chlorantha Sw., Orthilia secunda (L.) House, Chimaphila umbellata (L.) W. Bart., Moneses uniflora (L.) Gray) were explored. Root samples were processed for light, fluorescence, and laser scanning confocal, scanning electron, and transmission electron microscopy, as well as for immunocytochemistry. Roots of all species had enlarged epidermal cells containing hyphal complexes, Hartig nets confined to the epidermis, and mantles. Epidermal cells were penetrated by hyphae originating from the Hartig net at more than one site either …